Equivalent in-plane elastic modulus of honeycomb sandwich in the direction of cell vertical wall

Abstract

The equivalent in-plane elastic modulus $(E_y^S)$ of a honeycomb sandwich in the direction of cell vertical wall can be assessed by the law of mixture from the modulus of face sheet $(E_p)$ and the equivalent modulus of honeycomb core $(E_y^C)$ . However, significant errors as large as 40% can be made depending on material and geometry parameters, when the used $E_y^C$ is obtained from a cellular model of core alone without considering the skin effect of face sheet. The main reason of the error is that the rigidity to deformation of y-direction is different greatly between the vertical cell wall of core and inclined cell wall of core. In the present paper, an analytical model is proposed to assess $E_y^S$ of honeycomb sandwich with considering the interference effect of the core with the face sheet. In the proposed model, the influence of the face sheet rigidity on $E_y^S$ is taken into account. The results demonstrate that the contribution of the core to $E_y^S$ is also dependent on the face sheet rigidity significantly. The validity of presented model is verified by comparing the results with numerical results of FEA.